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X-ray ARRT
Radiology Registry
| Term | Definition |
|---|---|
| Photoelectric Interaction | Ionization. The photon strikes a K-shell electron & is completely absorbed --> electron getting ejected. Produces radiographic contrast as a result of the differential absorption of the incoming x-ray photons in the body's tissues. |
| Compton Interaction | Ionization. Partial transfer of energy from photon--> outer shell electron, removing it from orbit. Produces recoil electron & incident xray photon scatters. Loses contrast b/c photons lose energy when they change direction. Most common inter. in body. |
| Coherent Interaction | (i.e. classical) Ionization doesn't occur b/c the electron is not removed, but vibrate (no transfer of energy). Loses contrast b/c some photons lose energy when they change direction. |
| Pair Production Interaction | Does not occur in Radiography. The incident x-ray escapes interaction w/electrons but interacts with the nucleus of an atom, causing the x-ray to disappear. |
| Neurogenic Shock | Failure of arterial resistance -->causes blood to pool in peripheral vessels due to an injury in the nervous system (head/spinal trauma). |
| Hypovolemic Shock | Follows loss of large amount of blood/plasma. |
| Septic Shock | Occurs when toxins produced during massive infection that increases capillary permeability -->cause a dramatic decrease in blood pressure |
| Cardiogenic Shock | Results from cardiac failure or other interference w/heart function. |
| Gray | A unit of absorbed dose in tissue. # radiation present in the beam that is absorbed by the pt. |
| Sievert | A unit of effective/equivalent dose. Includes ionizing effects of xray/gamma/beta rays & particle radiation. Uses conversion factors that compare the type of radiation to biological effects. |
| Coulombs/kilogram | A unit of radiation exposure in the air (xray beam). |
| Becquerel | Unit of radioactivity. # atoms decaying/sec. Only used for Nuc Med. |
| Linear Energy Transfer | Amount of energy deposited by radiation per unit length of tissue. The greater the rad, the greater the biological damage. Alpha & neutrons are high, xrays & gamma rays are low. |
| Relative Biological Effectiveness | Ability to produce biological damage; varies with LET. The greater the radiation, the greater the biological damage. |
| Autotransformer | (i.e variable transformer) Varies the voltage (kVp selector) going to the primary coil for the step-up transformer. Operates on principle of self-induction. Needs AC to operate. |
| Rectifier | Responsible for current conversion. Changes AC-->DC. Made of solid-state silcon-based n-type & d-type diodes |
| Step up/down transformer | Operates on principle of mutual induction. Needs AC to operate. Change electric voltage/current into higher/lower values. |
| Rheostat | The mA selector. Type of variable resistor. Controls filament temp by adjusting the resistance that is applied to the filament. Measures the current flowing into the xray tube. |
| Attenuation | Absorption and scatter (loss of intensity) of the xray beam as it passes thru the pt. The IR receives a greater # of high-energy photons b/c the lower energy ones are absorbed by the pt. |
| Bremsstrahlung Production | When an incident electron gets driven off path by the nucleus & slows down, changing direction. Reduction in K.E. produces an xray photon. Most diagnostic levels of x-rays are produced this way (90%). Responsible for heterogeneous nature of the xray beam. |
| Characteristic Production | When an incident electron knocks an orbital electron out of orbit. When space filled in, the diff. in changing energy levels = xray photon. Energy is depend. upon the binding energies of the target material (only above 70 kVp). Cascade effect. |
| Stochastic Effects | (i.e. probabilistic) Randomly occurring effects of radiation; the probability of such effects is proportional to the dose (increased dose = increased probability, not severity, of effects). |
| Deterministic Effects | Effects of radiation that become more severe at high levels of radiation exposure and do not occur below a certain threshold (cartaracts). Linear-nonthreshold dose curve response. |
| Somatic Effects | Effects of radiation on the body being radiated. 46 chromosomes. Mitosis. Early: Hematopoietic, GI, CNS syndromes = death Late: Cancer, cataracts, shortened lifespan, embryologic effects (1st trimester). |
| Genetic Effects | Effects of radiation on the genetic code of a cell; affects the next generation. 23 chromosomes. Meiosis. |
| Direct Effect | Effect that occurs when radiation directly strikes DNA in the cellular nucleus. |
| Indirect Effect | Effect that occurs when radiation strikes the water molecules in the cytoplasm of the cell (radiolysis). Creates free radicals; HOH+ and e- Can create H2O2 & H+ |
| Syncope | Fainting. A mild form of shock. The bp lowers, heart slows and blood vessels increase--> low O2. |
| Blood pressure | Measured in systolic pressure/diastolic pressure. Normal 120/80. |
| OSL dosimeter | Optically Stimulated Luminescence. Uses aluminum oxide to detect. Measures as low as 10µGy. Must change 4x/yr. |
| TLD dosimeter | Thermoluminescent. Uses lithium fluoride crystals to detect. Measures as low as 50µGy. Lasts longer than film. |
| Film dosimeter | Uses film, aluminum copper filters, plastic case. Measures energy low as 100µGy. Must change monthly. Sensitive to temp/humidity. |
| Grid Frequency | Strips per inch. As the frequency increases, the thickness of the strips decreases. Ranges from 60-150 in. |
| Grid Ratio | The Height of the lead strips/by the Distance between the lead strips aluminum interspacers). H/D. 5:1 (2), 6:1 (3), 8:1 (4), 12:1 (5), 16:1 (6). |
| Grid Conversion Factor | (i.e. bucky factor) Amount needed to change mAs for using/not using a grid. No grid-->grid = mAsXGCF Grid-->no grid = mAs/GCF |
| Single phase generator | Requires pulsating DC. 4 diodes. Voltage drops to 0 every 120/sec. 2 pulses/cycle. 100% ripple. |
| Three phase, six pulse generator | Requires pulsating DC. 6 diodes. Voltage never drops to 0 b/c 3-phase current. 360/sec. 13% ripple. Uses 87% kVp set. Produces 35% higher average energy (kVp) than single |
| Three phase, twelve pulse generator | Requires pulsating DC. 12 diodes. Voltage never drops to 0 b/c 3-phase current. 720/sec. 4% ripple. Uses 96% kVp set. Produces 41% higher average energy (kVp) than single |
| High Frequency generator | Requires pulsating DC. 12 diodes. Voltage never drops to 0. 1% ripple. Uses 99% kVp set. |
| Molecule | A compound's smallest component, which still has the characteristics of the compound. |
| Atom | the smallest particle of an element capable of entering into a reaction |
| Element | a substance made up of atoms with the same atomic number and the same chemical properties; it cannot be broken down further without changing its chemical properties. |
| Grid contrast improvement factor | The measure of a grid's ability to enhance contrast. Expressed as the ratio of the contrast w/ a grid to the contrast w/o a grid. Represented by the letter "K" |
| Grid selectivity | A ratio of how much scatter vs primary beam the grid removes. The higher the grid frequency & grid ratio, the more selective it will be when absorbing scatter |
| Grid radius | the SID at which a focused grid must be used. The focal range is narrow for high-ratio grids; there is a greater chance for cutoff to occur. |
| Off-level grid | A grid error that will result in an image that shows decreased IR exposure across the entire radiograph. No portion of the beam has a clear path through the grid, resulting in decreased density visible over the entire radiograph. |
| Lateral decentering of grid | A grid error that will result in visible cutoff more to 1 side of the radiograph. |
| Grid-focus decentering | A grid error that will result in an image that shows normal density in the middle but decreased density on the sides. Caused by a violation of the grid radius. |
| Upside down grid | A grid error that will result in an image that shows normal IR exposure in the middle but decreased IR exposure on the sides & may follow removal/ replacement of the grid |
| Radiation Weighting Factor | Used to modify the absorbed dose amount to account for the greater damage inflicted by some forms of ionizing radiation. |
| Scaphoid fx | tenderness in the anatomical snuffbox (overlies the scaphoid/radial artery). A depression formed when the thumb is abducted & extended by 2 tendons of the thumb. Most commonly fractured carpal bone. |
| Colles fx | the distal radius w/ post. displacement. Typically, the result of a fall on the outstretched hand. |
| Bennett fx | @ base of the 1st metacarpal |
| Boxer fx | a transverse fracture of the neck of the 5th metacarpal marked by palmar angulation of the distal fracture fragment. |
| Pott fx | 1 of the medial & lateral malleoli of the ankle w/ ankle joint dislocation. |
| Trimalleolar fx | of the post. portion of the tibia & the medial & lateral malleoli. |
| Jefferson fx | Comminuted fx of the ring of the atlas (ant&post). |
| Hangman fx | C2 arch fx & subuxation of C2 onto C3. Cause by MVA & acute hyperextsnion of the head. |
| Seatbelt fx | Transverse lumbar fx & abdominal injuries |
Created by:
Crimsondrop7
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